Aerodynamic seal for face masks



April 14, 1959 J. N. FRESH ET AL 2,881,444

AERODYNAMIC. SEAL FOR FACE MASKS Filed May 14, 1956 m S P W R E mH NNSM. R E 0 V D T 1. M R

H ma Unie tate P e 7 2,881,444 AERODYNAMIC SEAL non FACE MASKS John N.Fresh and RichardD. Murphy, Bethesda, Md.

' Application May 14, 1956, sans... ss4,sss

ZClaims. cu-9 (Granted under Title as, Us. cost 1952 see. 266) Theinvention described herein may be manufactured andused by or for theGovernment of the United States of America for governmental purposeswithout the payment of any royalties thereon or therefor.

' This invention relates 'to face masks or shields and more particularlyto a face seal for open-ended wind masks which permits such masks to beworn for extended periods of time without imposing discomfort due toheadband pressures necessary to" keep them substantially airtight aboutthe wearers face.

Prior art open'ended air-stagnating-wind masks encii'cling portions of awearer's face 'a're'adapted to protect a wearers face, and particularlyhis, eyes against the hazards of high winds and/or extremecold. Sealingabout the face is-required-toprevent'l'achrymation and is usuallyeffected through a resilient'b'ead or the like about thefacecontacting-periphery" of the mask. A strap is*usually-employed-tomaintain the bead pressed against the face.

Because such masks are worn over protracted periods of time comfort is aprime consideration. In the prior art, severe headband pressures wererequired to effect proper sealing against wind pressures buffeting themask from different angles. These pressures produced discomfort aboutthe face and headaches after prolonged wear. Further, since masks arenot usually manufactured for particular individuals, and due todifferent facial contours, sealing, in many instances, could only beeffected by employing headband pressures which deformed the masks. Suchan expedient reduced the effect of the seal and multiplied thedeleterious effects on the wearer. Such an expedient also reduced thetime the mask could be worn and affected the alertness of the wearerduring the time it could be worn.

The instant invention provides a face seal for a face mask which givesgreater comfort over longer periods of time by reducing headbandpressures necessary to provide efficient sealing. The seal comprisesgenerally a thin circumferential flap and a plurality of spaced annularelements all integral with the mask frame, and wherein said elementsform a plurality of air passages which act individually to seal the maskby taking advantage of the stagnation pressures in the mask, andtogether to provide a comfortable resilient cushion through distributionof pressures over a greater area of the face. The frame of the sealfurther incorporates a bellows which in combination with said cushionenables the mask to adapt to a variety of facial contours, eliminatingthe need for severe headband pressures which would tend to deform theframe about the face contacting periphery, without impairing sealingaction.

An object of the invention is to provide a face mask employing anaerodynamic seal which enables it to be worn comfortably for extendedperiods of time.

Another object of the invention is the provision of a seal for a windmask which conforms to a variety of facial contours while eliminatingthe requirement of severe headband pressures to effect sealing.

A further object of the invention is the provision of a face seal for awind mask which utilizes the difference in pressures between ambient andthe pressures within the mask to render the mask substantially airtight.

Another object of the invention is the provision of a seal for a windmask which acts positively to render the seal more airtight upon theoccurrence of leaks therearound.

Still another object is to providea cushion and seal which renders theabrasion against a wearers face negligible.

Other objects and many of the attendant advantages of this inventionwill be readily appreciated as the same becomes better understood byreference to the following detail description when considered inconnection with the accompanying drawings wherein:

Fig. 1 is a perspective view of a goggle-type wind mask in accordancewith the invention;

Fig. 2 is a plan view in elevation of the wind mask of Fig. 1; and

Fig. 3 is a longitudinal cross sectional viewof the wind of a goggletype contoured in accordance with an average.

facial structure. The mask :5 is secured to a wearers face 6 as by astrap 7 or the like adapted to hold a seal and cushion generallydesignated by reference 8 (Fig. 3) against said wearers face. It is tobe understood that the instant invention may be utilized with'faceshields which protect the whole of a wearers face or with breather typemasks which cover only the nose and mouth portions of the wearers face.

Specifically the wind mask comprises an annular substantially ellipticalrelatively resilient tubular frame body member 9 of rubber or plasticcomposition. Secured to the frame body member 9 by any suitable methodis a tubular open-ended transparent wind shield 10 made of plastic orthe like, having good temperature stability over wide ranges. The strap7 of resilient material or nonresilient material with means forpositively adjusting it in length is provided and secured as at 11 tothe frame member 9 by any appropriate means.

Considering the mask by itself, the face contacting edge (Fig. 3) of theframe member 9 incorporates the seal and cushion 8 which comprises afringe with a plurality of oval elements 12. The outermost element is anoval flap 13 substantially parallel to the longitudinal axis of theframe body member 9 adapted to flare outwardly against the wearers faceduring use. The remaining elements are oval ridge-like projections orfingers 14 integral with or originating from a thickened portion of theframe body material 9. Each of the fingers or elements 13 and 14 is muchthinner than the main portion of the frame member 9 from which itextends. These fingers 14 project inwardly at an acute angle andincrease in length toward the axis of the mask. Oval spaces 15 betweenthe projections 14 are such as to form a plurality of air passages whichtogether with the projections 14 act collectively to form a flexiblecushion against the wearers face and individually to provide a.plurality of seals about the wearers face as will he described later.Intermediate of the frame body 9 between the cushion and seal 8 and thetransparent shield 10 are provided two wedge-shaped depressions 16 onthe opposite short sides of the elliptical frame member 9 Patented Apr-f14, 1959* The principle of operation of the seal and cushion describedis to divide the total pressure differential between the inside-andvoutside of. themask into, a series. of smaller differentialpressuresacross each of. the elements. IZ Inasmuch as; the reaction of agiven pressure differential. .by a single element determines. the normal,force hetween. .that,element orlsealand the face, assuming the sealperfectly fits theface, dividing that same pressure differential byemployinga plurality. ofelements 12 distributes the normal.force orpressure against the face and thereby reducesthat pressure underthe sameatmospheric conditions to give a cushioning effect. v

wI use the-outermost element orlfl ap 13.:splays outwardly ,ofthewearersface and the othenelements-or projections 14 deflect inwardlyof the wearers face. The spaces. 15 between;projections14. entrapairwwhen in usevandnvarious pressure .levels,across.themulti-element2:1;

seal aremaintained b'y slight leakagefrom each element 12. to anadjacentone inthe directionof, decreasing staticpressure. This slight leakage.is not objectionable so long as, the velocities adjacent the Wearerseyes do not produce lachrymation. Should leakage past one. of the ele-.mental} become-appreciable the local static pressureat the leak will bereduced in accordance with the aerodynamic principle of pressurereduction with .increased velocity of flow. This reduction of pressureat the leak due to flow in an adjacent air passage 15 willcause the nextadjacent projectionor. finger 14 to .be drawn toward the wearers faceresulting in an automatic sealing action.

1 The pliable fringe and bellows 16 in combination allow the automaticadaptation of the mask to. a variety of. facial structureswithout thenecessity for the utilization of headband pressures which-would tend todeform the mask and impair the seal, Any depression infacial contourswill be sealed by individualprojections14 notbeing depressed tothe samedegree as they would be over a' convex portion of the wearer's face.The" action of thewbellowsu lfi isradapted torallow thernask to adjustto faces of varying width with limited deformation of the seal portionof the frame body.

Obviously many modifications and variations of the present invention arepossible in the light of the above teachings. It is therefore to beunderstood that within the scope of the appended claim's the inventionmay be practiced otherwisethan as specifically. described What isclaimed is #15. A mask of a type .describedkomprisin'g a -"frame memberof voval shap e, said frame-,membenhaving a bellow-like constinct'io'n''at' its sides centrallythereof, a

1,. flexible seal at the face end'of said ;frame member adaptedtowardthe, otherendof said mask.

to ea the ma ktq a. we r rs fa e an str rz mea s for securing the -mask"to" the head-ofthe Wearerfsa'idstrap means being secured to said framemember between said bellow-like construction and said seal.

2., Ai-mask asdefined .in, claim .1, but further-characterizedbysaidsealcomprisinga plurality of 'flexiblefingers and a flexible :flap,Saidfingersbeing adapted. to: splay inwardly on the wearersface, andbeing. slightly graduated transversely, being. relatively. longer in adirection I v ReferencesCited in the patent I UNITED STATESlATENTSFOREIGN PATENTS France.... Sept. 29, 1954

